docs: def as_ufloat(roorealvar):
      """
      Cast a `RooRealVar` to an `uncertainties.ufloat`
      """
      if isinstance(roorealvar, (U.AffineScalarFunc, U.Variable)):
          return roorealvar
      return U.ufloat((roorealvar.getVal(), roorealvar.getError()))